Might be an overkilll.... I would think 1 gallon would do it. If I buy a can of it, do they have something that can put it in to pressurized it to use it like a spray can (I'm thinking about usage after I flush out the system)

I don't know what brake cleaner would do to plastic.... I can research it. At least I know it is available in large quantities. Looks like the Scirocco (yeah yeah, it ain't cables) is going to get DOT 4 over the winter.